Clinical applications of two-color telomeric fluorescence in situ hybridization for prenatal diagnosis: Identification of chromosomal translocation in five families with recurrent miscarriages or a child with multiple congenital anomalies

Two-color fluorescence in situ hybridization (FISH) analysis using human ch romosome arm-specific telomeric probes (telomeric probes) was used successf ully to detect each derivative chromosome of a translocation carrier in fiv e couples who requested a prenatal diagnosis in future pregnancies. Most of the human chromosome terminal bands are G-band-negative, and even FISH ana lysis using whole-chromosome painting (wcp) probes are often of insufficien t complexity to detect subtle chromosomal changes. A complete set of human telomeric probes was developed to improve the sensitivity of diagnosis of m icrodeletions or other cryptic rearrangements in telomeric regions. Two-col or telomeric FISH was the only possible method for precise prenatal diagnos is of one of the couples, because the carrier's chromosomal aberration was too subtle to be detected by wcp FISH or conventional methods. We have demo nstrated that two-color telomeric FISH has the potential to be a powerful n ew tool in the detection of cryptic chromosomal rearrangements involving te lomeric regions in prenatal diagnosis precisely and in time.